HMD Calibration via Portable Docking Station with Fiducial Targets
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Solution Overview
Problem
Head-mounted displays (HMDs) in artificial reality systems face challenges in maintaining calibration over time, leading to performance degradation due to drift in key parameters, which is often unnoticed and requires costly re-calibration at manufacturing centers, rather than being addressed in the field.
Innovation Solution
A portable docking station with calibration targets and fixtures or fiducial marks is used to calibrate image capture devices, displays, sensors, and illuminators in HMDs, allowing for on-field recalibration and charging, triggered by the HMD's presence and battery level, using a calibration engine to determine intrinsic and extrinsic parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If HMD calibration is performed at manufacturing centers, then calibration accuracy is maintained, but user convenience deteriorates and maintenance cost increases
Solution Approach 1:
The system enables the HMD to perform self-calibration by capturing images of calibration targets with its own image capture devices and processing the data through a calibration engine, eliminating the need for external manufacturing center intervention while maintaining calibration accuracy
Solution Approach 2:
Calibration targets (checkerboard patterns or convex reflectors) are introduced as intermediaries between the HMD and the calibration process, enabling the HMD to determine intrinsic and extrinsic parameters of its image capture devices through image analysis
2Measurement precision
If HMD calibration is performed at manufacturing centers, then calibration accuracy is maintained, but maintenance cost increases
Solution Approach 1:
The HMD performs its own calibration using onboard image capture devices and a calibration engine, eliminating the need for costly external manufacturing center services while maintaining calibration accuracy through automated image processing and parameter determination
Solution Approach 2:
The calibration system is integrated into the HMD itself, allowing the same device to both capture images and perform calibration processing, eliminating the need for separate manufacturing center calibration services
3Reliability
If calibration is performed as a separate maintenance step, then calibration thoroughness is ensured, but user burden increases
Solution Approach 1:
The calibration process is merged with the charging process, so that when the HMD is placed in the portable docking station for charging, calibration is automatically performed using the docking station's calibration targets, eliminating the need for separate calibration maintenance steps
Solution Approach 2:
The system performs calibration automatically when the HMD is placed in the docking station, determining intrinsic and extrinsic parameters before the user needs to use the HMD, so calibration is completed in advance without requiring user intervention during operation
Data Source
AI summary
A system is describes that includes a head mounted display (HMD) and a portable docking station configured to receive the HMD for calibration of one or more components of the HMD. The portable docking station includes at least one calibration target, e.g., a checkerboard pattern and/or a convex reflector. Techniques of this disclosure include calibrating an image capture device of the HMD based on one or more images of the calibration target captured by the image capture device when the HMD is placed in the portable docking station. The disclosed techniques may be applied to calibrate multiple different components of the HMD, including image capture devices such as eye-tracking cameras and inside-out cameras, displays, illuminators, sensors, and the like. In some examples, a rechargeable battery of the HMD may be charged when the HMD is placed in the portable docking station.